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Science > Cell Structure + Cell division- biology paper1 > Flashcards

Cell Structure + Cell division- biology paper1 Flashcards

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Biology 101 flashcards
1
Q

What type of cells are bacterial cells?

A

Prokaryotes

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2
Q

Why are microscopes useful?

A

Because they allow us to see individual cells and their sub-cellular structures, which we wouldn’t be able to see with the naked eye.

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3
Q

What are the 2 types of microscope?

A

Light and electron

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4
Q

What do light microscopes do?

A

They use light and lenses to form an image of a specimen and magnify them. With a light microscope, you can see individual cells and large subcellular structures such as the nucleus.

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5
Q

What do electron microscopes do?

A

They use electrons to form an image. They have a much higher magnification and resolution than light microscopes. So, we can see much smaller things in detail, like the internal structure of mitochondria and chloroplasts. We can even see tinier things like ribosomes and plasmids.

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6
Q

What is another name for the resolving power?

A

The resolution

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7
Q

What is the resolution of a light microscope?

A

around 0.2 μm, or 200 nm. This means that it cannot distinguish two points closer than 200 nm.

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8
Q

What are the 2 types of electron microscope?

A

The scanning electron microscope (SEM) and The transmission electron microscope (TEM)

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9
Q

What is the highest magnification of a light microscope?

A

X 2000

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10
Q

What is the highest magnification of an electron microscope?

A

X 2million

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11
Q

What is the resolution of a scanning electron microscope (SEM)?

A

10nm

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12
Q

What is the resolution of a transmission electron microscope (TEM)?

A

0.1nm

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13
Q

What is a field of view?

A

The area seen when looking through a microscope

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14
Q

The SEM microscope…

A

has a large field of view so can be used to examine the surface structure of specimens. SEMs are often used at lower magnifications.

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15
Q

The TEM microscope…

A

is used to examine thin slices or sections of cells or tissues.

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16
Q

What is the magnification of a TEM microscope

A

X 1 million

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17
Q

How do you prepare a slide using a light microscope?

A

1) Add a drop of water to the middle of a clean slide
2) Cut up some onion and seperate it out into layers. Use tweezers to peel off some epidermal tissue from the bottom of one of the layers
3) Using tweezers, place the epidermal tissue into the water on the slide
4) Add a drop of iodine solution, Iodine solution is a stain. Stains are used to highlight objects in a cell by adding colour to them.
5) Place a cover slip on top. To do this, stand the cover slip upright on the slide, next to the water droplet. Then carefully tilt and lower it so it covers the specimen.

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18
Q

What is eosin used for?

A

Making the cytoplasm show up

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19
Q

How do you observe a specimen using a light microscope?

A

1) Clip the slide you’ve prepared onto the stage
2) Select the lowest-powered objective lens (the one that produces the lowest magnification)
3) Use the course adjustment knob to move the stage up to just below the objective lens.
4) Look down on the eyepiece. Use the course adjustment knob to move the stage downwards until the image is roughly into focus.
5) Adjust the focus with the fine adjustment knob, until you get a clear image of what’s on the slide.
6) If you need to see the slide with greater magnification, swap to a higher-powered objective lens and re-focus.

20
Q

Why do cells differentiate?

A

Cells differentiate in order to develop their sub-cellular structures so that they can change into different types of cells and carry out specific functions

21
Q

Give 3 ways a sperm cell is adapted to swimming to an egg cell

A
  • The sperm has enzymes in ts head to digest through the cell membrane of the egg
  • The sperm has a long tail and a streamlined head to help it swim to the egg faster
  • The sperm contains many mitochondria to provide the energy needed for movement
22
Q

Why are nerve cells long

A

So that they can cover more distance

23
Q

What are embryonic stem cells

A

Undifferntiated cells found in human embryos. They have the potential to differntiate into any kind of cell at all.

24
Q

Apart from the embryo, where else are stem cells found in the human body

A

The bone marrow. However, stem cells from the bone marrow can only differentiate into certain cells, like blood cells

25
Q

Where are the stem cells in plants found

A

The meristems

26
Q

Why are some people opposed to the idea of using human embryos in stem cell research?

A

Some people think that stem cells are a potential human life.

27
Q

What are chromsones

A

Coiled up lenghts of DNA molecules.

28
Q

What are genes

A

Sections of chromones that control the development of different characteristics e.g. hair colour.

29
Q

What is mitosis

A

Cell division

30
Q

What is the name of the process that bacteria use to divide

A

Binary fission

31
Q

What is the maximum temperature microorganisms in a school lab can be grown and why?

A

25 degrees Celsius, otherwise harmful pathogens may be grown uncontrollably

32
Q

How can you make sure the experiment that tests the effect of antibiotics on bacteria is not contamianted

A
  • The petri dishes and culture should be sterilised before use to kill any unwanted microorganisms
  • The inoculating loop should be sterilised by passing it through a hot flame
  • After transferring the bacteria, the lid of the petri dish should be lightly taped on - to stop microorganisms from the air from getting in
  • The petri dish should be stored upside down- to stop drops of condensation falling onto the agar surface.
33
Q

Describe the experiment that tests the effect of antibiotics on bateria

A

1) Place paper disks soaked in differnt types of antibiotics on an agar plate that has an even covering of bacteria
2) The antibiotics should soak into the agar jelly. Antibiotic-resistant bacteria will continue to grow on the agar areound the paer disks, but non-resistant starins wll die. A clear area will be left where the bacteria have died(inhibition zone).
3) A control should be used- a paper disk that has been soaked insterile water instead of in antibiotics
4) The plate should be left at 25 degrees Celsius for 48hrs.
5 The more effective the antibiotic is against the bacteria, the larger the inhibition zone will be.

34
Q

What is diffusion

A

The movement of particles from an area of high concentration to an area of low concentration.- down the concentration gradient

35
Q

Name substances that can diffuse through cell mebranes

A

Oxygen , carbon dioxide, glucose, amino acids, water

36
Q

Name substances that can’t diffuse through cell membranes

A

Starch and proteins

37
Q

What type of molecules move by osmosis

A

water

38
Q

What are the 2 main differences between active transport and diffusion

A

Active transport requires energy- diffusion does not
During active transport, particles move up the concentration gradient. Whereas they move down the concentration gradient.

39
Q

Describe the steps of the cell cycle

A

-Growth and replication(interphase)
>The DNA is spread out in long strings
>The cell grows and increases the amount of sub-cellular structures, such as mitochondria and ribsosmes
>The cell replicates its DNA

-Mitosis
>The chromosnes line up at the centre of the cell and the cell fibres pull them apart. One set of chromosnes is pulled to each end of the cell
>Membranes form around each of the sets of chromosnes. These become the nuclei of the 2 new cells(the nuclei have divided)
>Lastly, the cytoplasm and the cell membrane divide

2 identical daughter cells have now been produced.

40
Q

Which ways are the villi in the small intestine adapted for the absorption of digested food

A
  • A singe layer of surface cells, short diffusion path

- Surrounded by a network of capillaries and good blood supply, quick absorption

41
Q

What happens to unwanted stem cells from fertility clinics anyways?

A

They would get destroyed if not used for research so some people argue that they might as well be used

42
Q

What are the advantages of stem cells in plants?

A

Throughout the plant’s entire life, cells in the meristem tissue can differentiate into any type of plant cell.These stem cells could then be used to produce clone of plants quickly and cheaply

Consequent, plants of rare species can be grown and crops with desired features could also be grown .

43
Q

What is binary fission?

A

The process by which prokaryotic bacterial cells divide

44
Q

Describe the steps of binary fission

A

1) The circular DNA and plasmids replicate
2) The cell gets bigger and circular DNA strands move to opposite ends of the cell
3) The cytoplasm begins to divide and new cell walls begin to form
4) The cytoplasm divides and 2 daughter cells are produced

45
Q

The daughter cells produced through binary fission…

A

have one copy of the chromomal DNA, but can have a variable number of copies of plasmids

Science (31 decks)

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